NAME

SYNOPSIS

DESCRIPTION

CSS::Minifier::XS is a CSS "minifier"; its designed to remove un-necessary whitespace and comments from CSS files, while also not breaking the CSS.

CSS::Minifier::XS is similar in function to CSS::Minifier, but is substantially faster as its written in XS and not just pure Perl.

METHODS

minify($css)

Minifies the given $css, returning the minified CSS back to the caller.

HOW IT WORKS

CSS::Minifier::XS minifies the CSS by removing un-necessary whitespace from CSS documents. Comment blocks are also removed, except when (a) they contain the word "copyright" in them, or (b) they're needed to implement the "Mac/IE Comment Hack".

Internally, the minification is done by taking multiple passes through the CSS document:

Pass 1: Tokenize

First, we go through and parse the CSS document into a series of tokens internally. The tokenizing process does not check to make sure that you've got syntactically valid CSS, it just breaks up the text into a stream of tokens suitable for processing by the subsequent stages.

Pass 2: Collapse

We then march through the token list and collapse certain tokens down to their smallest possible representation. If they're still included in the final results we only want to include them at their shortest.

Whitespace

Runs of multiple whitespace characters are reduced down to a single whitespace character. If the whitespace contains any "end of line" (EOL) characters, then the end result is the first EOL character encountered. Otherwise, the result is the first whitespace character in the run.

Comments

Comments implementing the "Mac/IE Comment Hack" are collapsed down to the smallest possible comment that would still implement the hack ("/*\*/" to start the hack, and "/**/" to end it).

Zero Units

Zero Units (e.g. "0px") are reduced down to just "0", as the CSS specification indicates that the unit is not required when its a zero value.

Pass 3: Pruning

We then go back through the token list and prune and remove un-necessary tokens.